I've never heard of that claim. All I'm aware of is the NDSP bashing and promulgating anti-Communist lies before/as Hitler came to power.

"Dialectical materialism works like cocaine, let's say. If you sniff it once or twice, it may not change your life. If you use it day after day, though, it will make you into an addict, a different man." -Nicolae Ceauşescu

You mean the NSDAP, and they did work together in one occasion, at a strike somewhere in Prussia. Specifically, I believe it was a cooperation of unions (NSBO = nationalsozialistische Betriebszellenorganisation = National Socialist Factory Cell Organization and RGO = revolutionäre Gewerkschaftsopposition = Revolutionary Union Opposition) rather than parties, though.